Rhododendron 'Conleb'

Summary

Mortality for this azalea on the two lowest irrigation treatments was 33% for 20% of ETo and 17% for 40% ETo. For this reason, we would not recommend irrigating at less than 60% of ETo, the high end of moderate irrigation. Best overall foliage appearance was on the highest irrigation treatment of 80% of ETo. This was the only irrigation treatment which produced acceptable foliage health throughout the summer, except for August, when even this treatment fell below a 3 (Table 17). Leaves on all levels showed tip burn most likely due to the boron in the irrigation water, though it could also have just been water stress. Late in the summer, plants on less than 80% ETo irrigation showed signs of heat stress such as wilting and browning.  The plants bloomed from December to March with brilliant burnt orange flowers, but did not show the promised autumn re-bloom (except for one plant on 80% of ETo in October) in our trial protocol, though more blooms may have appeared later in the month had the plants not been removed. There were also signs of chlorosis in some plants early on; our soil is a neutral 7 pH, and these might benefit from slightly more acidic soil. The average width at the end of two years was 17” (43.5cm) and average height was 13.7” (34.7cm); there were no significant differences in average overall growth between treatments except in September between the 80% and 40% treatments.

Growth and Quality Data

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